SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97ccbb11027be964b1af11ef90a9512a83217f97ae9467cc7b63731c315dea42' 
  AND token = 'l9HJAhzIwUZZymtzXeUX86GvAuBvvpdBfrTtyRRhhn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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