SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2cbd740174105740ef7a73fa19cd9b0f31220821258ba16d0b0ce2cfc8a587ec' 
  AND token = 'lCIdLZYucMSEvck9UTJZ/j6srC6JTvamTgXmxK+ZqC4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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