SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98682bac9b151716e5cccf85597135e1fcc692f683020e25d60f33f0c7a2f2a1' 
  AND token = 'CEdRxA4ABl0gPEnKI9KQI8c0QB1WB1BAApTfLhpESR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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