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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f31e0af486ecbcc357c8d9e6b6a54987a23f40ed24ed3340e451ffdd6f363970' 
  AND token = 'gPmqYtEij7JB8k47eUUuExeGGgCj77oYVkatk+d9P8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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