SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6af1c3ab7adbe21a72b0028d351678269c26f0e8b7bf35fc0c1c64ef355232d' 
  AND token = 'gVe0/exV1NSY2XZMLhxa+moky8Y7rZ4lpwtpcKwPi6k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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