SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7e3e50472f3aee8d6872db09576ed077a485116b360cf880d3a0becc9204aa3' 
  AND token = 'tn5vNPKaXwHpmXwfVZQr38aCGfr1SJsS29DfQqDCX+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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