SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8698ffbd6d5370e34b6471bf9ca1d7c9b77545fd0bc6ee76b4a146e47216615' 
  AND token = 'MxAv8hztCiISQTeoWV+le4+RdA7ycx7zA2nQnnFxZws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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