SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5754c09b00045b193ea62bbffdc05a8fb80cc33ffb11ade529ce8244b7ea724' 
  AND token = 'S0Fohca/Q090IpSWrOri52sT0cpHVOZLcDtcUvBPuPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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