SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '343445ed889a1e1040103851929482b1e71d2880c9c2f324449e4441bd774b5a' 
  AND token = '/pslEinwoefrUnFyRrijDNx9PF1qBIujWfdNK6BajR8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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