SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '07503935ef504a5ba34f95d9e3d1c8c312f08475c5e9fa993de0d17e2c593c97' 
  AND token = 'x5zQ/Ueqdc0FvDbw8Y+uWLPoatcdXHYPGRq2dKU+Iss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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