SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a52776032036bbae8874b398e56e2cd036163ac681096cdf04094d889fa5b9b8' 
  AND token = 'BQwnH+o7gherSk6mJBUIdCamByhINMUMYwodEPchtJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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