SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b58d4b62f2e44e78638232dbf051f1925713bf174d76f904ec685eb4e134a94' 
  AND token = 'UxvgtLyCl+jSYWU66HHBruNegnGcE7aD5UcxywioJNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}