SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90797b3aca587ffeeaa62a435b4db36bf35018677e996470051e3cf907273b7a' 
  AND token = 'kMPh+P9vheZ2ECgnrBS4/wrwKggyw56JGfblLr0GZ6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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