SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f14a6145c53ba91346d113e7774ad3da95eb3f4ba99846427009656ef409040' 
  AND token = 'r8RtKiLmfw2EDSJm+xflIIB+SInJs066tpBGLk081xs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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