SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43112dbb90c7625ef9383df659a6d5e919278a63dcef696622999dde0afd9f73' 
  AND token = '1oA0QGkRslWVJGzVB6fSwoS653o0OSmigrHVgHwZIyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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