SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '342e4341093bb95bd6d3ca0ad79b637481853924dc1c60af7bc10ea8222be9a8' 
  AND token = 'YYoVo+PErBi4fBcTvNKlTymyTnmyl/BxPAdkWLGwCQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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