SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0ac277889d4d929c153d833530363c211a7d1d0110c13743f8c8cf0cbe097337' 
  AND token = 'WJNuhTF4YlZE3Nxx9nMsgC3WkimaArJJxZmumGLveIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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