SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3dc93648b7ba8c28eaf271a962beb460aedfc84995931f495b22242e51c5ec1' 
  AND token = 'lTUTL+Z/Y1FzRW7Y91tCg2HvSSUPaXqJKxW/hegqhdA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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