SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a38fa9df02de2b6ed599e5e2e479ba2c7413e54d1016a3a2f649e89705e9fd78' 
  AND token = 'ADceK1jkRG8tzwzr4iZ8bqljeaMDP2Qu0YxTf+2QOpo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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