SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49652d458f9e3bbd142e0537a061a426e789094634706c19a87958f511b5303e' 
  AND token = 'lkMpLhoCt4TEIfiy2hcX3frYcKIzHkRk+G1F9ogDxFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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