SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a39feadde8b27d8501eb7651b0e8dcf902d3e668dccff7b5dbe2710482ca5e01' 
  AND token = 'e/HNOMUNl7PmsMaVFB4w5TRco+mSJQqfLTF/3XYgLeM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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