SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fed721462b0f1ef4df28e9e448c7a217e8aec35df6f05b8587afc540aa3a0fbc' 
  AND token = 'jpdpkTNUQvDfKZDEhgQAltfEo9o8wxsTROfOb8/IsGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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