SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bc96f85480408174310e682573c0a3ec3ac45ed5fe06da3e83edae7d3987de5' 
  AND token = 'ppODIF4Q3OwnWCVIB7sQkxrGR/CoPdn7hRyoxn9TWTU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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