SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5ef02aa2db9715f36908eef73c560a5e3a82026865a552e2ba213abac4dc7bc' 
  AND token = 'vu4hR/mw4EGRejQsKRzFIeY2SmB0vo/gxPObltjw6SU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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