SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5d4386ea231122e75e7e3704840a6d1271ca22ccfef967e726a8474d44b9b01' 
  AND token = 'PcRiVwou8WHhsSPWROSu21MQuFX7njYoDCy2ksdNhLE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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