SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '748fc12315c6c87f52df9b9c95718b71f00ba9fa048549527cececab8e85b3c0' 
  AND token = 'MCs+2kZIxCmemjJCG2YjHsXbKh83C/vtB5PoiMOp220=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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