SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd55c750b8b5c26fd2b15103e693cd613a3763de15ebf83b91d36a8a285a475c6' 
  AND token = 'vTfeJkMnGdgmN4tuJWHcybTNZwc1EKfq1bTQnBo73DA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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