SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98d3e7421410a37726bf34fdf3c26348dfb4dc35f24678606f9929894c745802' 
  AND token = 'OTiMS5yfU4KDex7y8q7BU2RPAh+213rSL1AWc3hmZbQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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