SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa5c2e50a108f8434e4eaae05eb0703154012d7ff5496443ce40669c367826b4' 
  AND token = 'Bd6jRDGBiJYXAcq+tmbdR34ugyVgdUkDp9+u2iQZ1Qg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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