SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aecd4cc300fddf07ed2960ba4db4d750611d97e2754625efc15925c7d3aafceb' 
  AND token = 'z+C2UN/fiKeqEU0680lVV6cYMXDHvhldpdansRx/56I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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