SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a8f981b0be4740425a6d2bbe621ed1b6ef5285bece0c7529ae7e9d7934f683f' 
  AND token = 'Z4Un0ixVveRoNYCmwC+FU2jBaAfXKnP4+MIsI/D2fkg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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