SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b137a3efa4d0865000bfb3727839340a2a8fa28518e45e2fd62159e587e17859' 
  AND token = 'yMH4ZsFp9DAFOYVsqjMWGtDgVU/FFKIUjimASOGjOmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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