SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7408fb79256e43057271bba1f0aa105e642fed14e92fc868bd79f486f305a313' 
  AND token = 'bSX4A7lVIpuoTKBe/e92SzysaTrbBI8VLoyNhMI21Ko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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