SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b797cf6eaaeccebf79ed0c6fffaba5ff0146c4f0c8ad88191b2a09cc3d7d48a0' 
  AND token = 'NLZvHauOnFpbNdM188/G9tptuv/T13a7JfFsR2bCxo4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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