SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1894270dd82772785db99e1c8f0ba231e2f4acd5024c3c9ca068a29875840a26' 
  AND token = 'rn0NsRRVoPgc5ss2uiDXRS6wDfE2YzD93aP/JZjTJvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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