SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '310e104a90254e93114b92203df365415373e06651901316ca68065c16aaa562' 
  AND token = 'uyNwQjhTbLUOUf1phibsGNmYxpK6C2MAabQ+nBfwWC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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