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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8c79ed5afaf97d2a86ae0e045c57e673df4be8032c3e637e7619558eeabe4cd' 
  AND token = '/UdUywkXCvZIElbtn2qPoInaD1iNrgUMxhSFzyWt0oI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}