SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8b52f6813ad53966aac9f9e5f2f58e07d9f3bae024285e3c7566df15eb6321d' 
  AND token = '2IEY4Qcq9xgZBl2cKxFVhV4wlrjNyNhoL4/EuauEdAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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