SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c85c0d430482608a8c11018474fe525a4fc0cb34b808ffc8a521b261bdf7715e' 
  AND token = 'Q/G0UlGrNwSMKLKamDfDjV0VwO5IMdGpgxCZ0EHVDkQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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