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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '253d0322bd53331dba2dc69876732eba8c63fe9a6c8e4085efd2ad1c833c50e7' 
  AND token = 'nYtAd/UZV5xqdBx0KEi8iFRJQ6nvrWFOB0VYKmQhLMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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