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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c15c1f56647f32e582c4850b8f03471500c92d1a4dc0a21444cd08a970f7b14e' 
  AND token = '+da4YgQ6Ifv4IB9PKqv8SYMb5mG0bRG9LvdrdRFD02A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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