SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '234d3e3cfba8f0e5d4cd0eb64df4cb734beb8c080468ffa1c1d19ac828546bac' 
  AND token = 'qaZKjqmURdS/FiGx9ynRqQhBSKgi/MgeC7lviAQVAMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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