SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7ae83bd7cf70fdbb9f80180c825428c4b332c6e2176e21bd10ab3e25072f37a' 
  AND token = 'Su5HuvTBS9+3Y/C3vexDh7PGOzwZYhaU96XM/JpxqnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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