SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7eb73f66acc13bea951b2c08dfee2f6745758a934bda648e1273fbe0693f831d' 
  AND token = 'nnxInaWyIDIDUWgEwLFO0irsiaMTvZFU3uS+O3rLE70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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