SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f62490c139634746d026213126834dfea06abb41e6e56409541dc775c636cdbc' 
  AND token = 'YVdIgoRBA00FsMR5Lx/WNVxOZiiluqIJoGNohxWjtEk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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