SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b91c74b5a3d1afce22a0c8cb9193a2dc4dac65c9ec862c02b389877ea220f58' 
  AND token = 'mA9IDGpVrFTlqmB5kQdgxjbkMO9zqrgbEKE+JcWG1Is=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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