SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3157d00c9e8223e6c10258ba6733459af584503bc6edf2100a7d477682bcccd7' 
  AND token = '0pldTVNQXuIHPaOnOXWZuseEBWw6RCWXF3y4a1U7LAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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