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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15e6b9ef0ea1bbfad86b6c0f9e79f02272b03810671e4f529f720a4cda9ce250' 
  AND token = '0cJhTS+pa4scWWbPne89Ot6RVcorPvrP98Yfu0jfGx8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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