SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bce31b4d5b49744aafde7970a455f40b6e8e1d28541c8c2a23b1085da784764' 
  AND token = 'mbt3Y7JTvVC1B48qzMMqeKRIcwkGgDxKMWf6A/IGDpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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