SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9520ce062f28507fd89b349cd40f161450c11695f54ca85483999d06e357ba47' 
  AND token = 'U3LfmhPlLg5eztC2qeLi2zNilTlQUMemxrjz4McwRq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}