SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab06588b74aa8f3a74f12ccc5107914c61c15fd4819acfa8dfb68045e402f2b4' 
  AND token = '7MxNGbdMobJUJetioRl8SGVs1djjxb/IZs6wqZkKrrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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