SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '732cbdb6d706ade1328a001c752f6d63143b23a9f69fcb223ddb58074f6e57d7' 
  AND token = 'UYr3EzVZAoR1+siZepO5/Kp8tNMl3w3sTtEMoskKeUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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