SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '24168fe61fd295521e366c3df083f7c9b242fc975d939ce2f16eb7c39833f34c' 
  AND token = 'ldCJuvH5Yimkq1xzIqVOwi1Mvp2/MZ/5Nz4scrqmqyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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