SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d38224b93845cd1fe432e7be43dc0cbd2f72af59281c7ee756fbe781c5f9ab2' 
  AND token = 'JyMfuGECzHk0tEIt1Ahw4vEra3vEXfBKBArPSwUd5ZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}