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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2251adb6e9233f0d92e69e1720476d3210fa959bedc1b0afc21d23bbb0a2556d' 
  AND token = '9vqR5duT9ZFVysDGmLH3ixfFBV3v4cE0VtvH0iIQW1E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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