SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ef929b200b789c9b552dbfab514982efa6ab368d9633a2bbe8791a23d16f440' 
  AND token = 'sd625sujt6LE1DAeSDFwyd/I86XiWUGhUckrwPki7qQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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