SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd926804882520458381359be379198ad9facef1c775ce6bfef45b2be769ddcb' 
  AND token = '0iWb1Jh1/+BW7sr8d5+LpXg0o0ciCpynGT5nJv2nmPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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