SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bec238dc0c62b53e559c640c756c6780807237291aa2168a103f281811b6e26' 
  AND token = 'IS3xPWPVxQKUVdYVRyYyNWNg+iVddxTxLvUIqcd7SPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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