SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '376de8b1233c7ba8939fe43c2651c7b249461cb245703a189d1080da73bcf394' 
  AND token = '1W3FR5pUa78V1FBuBpeXxN7+J/Ykzo3fC/Wmjq+XX4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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