SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '899b1295c058a0457a5bedc86b11f6281a80058039766dc70f33aaac45016ac2' 
  AND token = 'aAI/xX7ghebjObcq35Jt5268pGVS5rUXBy5G9LBGSjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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