SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f8ab09ff89c64e2b2738a66bc303132c05915420236b400ae269f406f58c669' 
  AND token = 'fZMN3CDC+kWgVHWzK3I45//dbbnis8Xk6abKSf5xURA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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