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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c19cd326a67b2b9a838ff706d2d11dff6d0eb25dbc565951fab7a9ba123065e' 
  AND token = 'em4jSlx7eGajZiktwSZH74zHF7WQ2IJny1JPexrESvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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