SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f510e935a5afded3b01c9db9e25cb64c182591d4cafbc1226a8688dde79a4b32' 
  AND token = 'uErIQYNMe5w433bikSE89s9XgIQGiuhOfJzdoZONr3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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