SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '199da5d79148217fd78a1ffcccfae285d337fb79cc48e9a28613b9aee3051598' 
  AND token = 'W6ekwMXiSAMlO+s+bGnGuQ8UamUJC1dWA+PqI1xKm7o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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