SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '857734d45b1734e5e49c59c5f1075fc9a075adb31345fadc03c0ca1df8378dc2' 
  AND token = 'xaLYtC2oEqeDqNJLZ8Qjy/Lx40ILZjOHwI5gzKyz1Lc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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