SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ce5ab2f03a9678698853be5a74aaef83552e7fdfa6eeb1e3ea19918f4218fdad' 
  AND token = '7x45zMTDPfMAuvnTfF75XRdoEzqm5m07H6JdcrmmeIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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