SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc31748f480e52976e0c86a025507313756919b2be865d89494dec04abd7a34e' 
  AND token = 'IrPpxLmWhSUhR1MqIFsueOVdGzV0PPBOXIRYzkbGShg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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