SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ef3c4da4cf2666dce04407ccdc9ac33ef1689bb22aed1fd6bf42a463fde3d6a' 
  AND token = 'btnmfshVXbDmPmtILAGhCkBBrFWjqagMX0TqBK6iXhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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