SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83904812fbcdaf5de172789924a3310e220b6e187b1ae053841faef21f012e5e' 
  AND token = 'uu+MI5MdLbOfRxtcAgYVqb43PZ0CUJf3FCrwBCNtLCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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