SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c71e0aebecd2df8f9a7834c955808a4c353c725e97f663ee2e7aabbdbbb51918' 
  AND token = '+WPVbgIowFXx9At9FITLAET59SKgDEgd8HEyOaA2P5E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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