SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e621b3da2a7919b6c7599995fd50410461f6177f1866b4c5fef6b4a1f6fdbb37' 
  AND token = 'KFnR0Wlexon8rzCVnq42I+WFRYgGZS687qCuWeRvyBs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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