SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6714fd6368aabeec3316d58393dff66370c61ae2926ca3b2850f4173df4da0b8' 
  AND token = '3N6qmImV6rK+Sx6SzzyI84jGxP+XhmJrPL0BtHVPInU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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