SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f756d44e84267f7e9f6a89055bf74e31a741acdf2176c40f0af072d02070d1d6' 
  AND token = 'fOB02GFTlgRhR4TzvuPfLbnUp/d445uUBuXOyIoK5vY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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