SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f605eba6ed631ead0175cd4679bae80120741803e5135b1123db7471bce0c57f' 
  AND token = 'mr6aWHSvzxLH2WVSe8MThrm+/Snby1UMmGzkyZKC07s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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