SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'abf99abd11cdeb789e10d30aac25598124d627e40964ed73d81be0f6eb2e535f' 
  AND token = 'eatXmHkp+YYDYuauNDZ89GRNI253kYmgWVXZnGlrdKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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