SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e36ce36a057f8d1bf310737e7bfa1366cbdfc34aaeba61a7225cc66057f385d' 
  AND token = '5Y6bYwY5RnjfXVxl2owpt8x5W7jZXki7Dqdrq7C+bsE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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