SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'edc2af618360254e4ce0316013f7c4b81fd2976d9bed59efab2813961fee8f4c' 
  AND token = 'Pzst5dwuH0yslL2G+9OAEISKx/rurHCKUx5VzmVhq90=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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