SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a2322bef9f2ed524955448589966f791754cdb00ce934b1f50212f3ef438d5f' 
  AND token = 'LT7yqYIdGvjqM5CDRRA1uEb4E4AzCcS2rdznzNqgMs4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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