SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c0e2541c67a4a554c0692779ebac5a0e94a0e0533cef355f9389347197c3a88' 
  AND token = 'qct08W2Ilm8p0L+U5/MwlbAXA4r+aaHnBA0V2uaLyVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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