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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fceb78d03b809c93cdca5c873b0de948297ed3341b5d224750dba7a79f7f6d34' 
  AND token = 'RXgI2qHwcFn+aGPCo6kDQAwUUTmi7/ihbq88SKl+lsA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}