SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d540b9fe4a89c3e3f98d16ed485321e29c551acb83df8d94c0228b349fe0d61' 
  AND token = 'v2pMwVMgIRfRj1pCJhVPDybhKmXr+E87sEHWmGCVZak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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