SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'edf83ec10c3cd5a63642289a0905ad709eced48fcb1aab68f837256572ca7b21' 
  AND token = 'yp3k/UyvBknvcysI5YjlyGoQVlnSQqk2w5jXbdg9yRE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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