SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7acd915bbc449ee9133a3426d9427108140fb274985218bd9c375c93357f1cad' 
  AND token = 'ouLrO/P5XjL++kGIY7XjGeWlpm+UiBPL1OXfep/rDn8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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