SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1e520d11888e011b0233dd45e2904fd6d07c5210b6b482d043750d3a48379c8' 
  AND token = 'DmJJtTGSrldrLKNoz5rbKwWZiqEBndboIm23/y6hLik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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