SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b38d75c439e0582c383c23812a7e1383a08585906506488e59b2459d3c0d803c' 
  AND token = 'ufrbn/fhyxyyPYmqn5KByIh1HjdgQyg6d9tbkfavEIE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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