SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '869dfa1b5929044fff6660ae88f539e40dffa965bb85a2d6de6a0236d1143239' 
  AND token = 'l79TEBWaBaSDnfO3i9YZU+aY8aXBzjPVeHgu7qsd7dc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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