SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0359c87ff90b68187da580cea393fb0b6158136a8261594185c79715af7a99c' 
  AND token = 'PiIpqJQhYFME01wor+QBjU/Gz2fv3nTAF3oUN96W2b0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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