SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23411dfa2834e5cce94908a0948864b63343467242b33fc8459fb9df2608e4c0' 
  AND token = 'VdAqCZf1Pw9LDLNSoU/x1ZgzXlyzpqcrI/3K7+6czno=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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