SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b65bfdc85fe274cb798401162c30de1cb7e078732e32afc001aecef94122aeef' 
  AND token = 'USG/ZccpuEoeIKnzhZ6662DzkSYbJknBtfi53kzXzT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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